Siemens SINAUT ST7 System Manual page 279

If a send message is entered using the image memory principle, only a reference to the
location of the message in the message image memory is entered. If the TIM has not yet
been able to transmit the message when the same message is transferred to it again, the
message is not entered in the send buffer a second time, but rather the image is simply
updated.
At the time of transmission, the message is sent with its latest content from the image
memory. Only then can the message be entered in the send buffer again.
Transmission using the image memory principle achieves the following:
● There is less load on transmission link, fewer messages are transmitted.
● There is less load on the send buffer of the TIM; an image memory message is entered a
See also → Image memory / send buffer
ISDN
(Integrated Services Digital Network)
ISDN integrates various services in one transmission network. ISDN networks integrate
telephone, telefax, teletext, Datex-J, video phones and data transfer. This makes a wide
variety of digital services available to the user: Language, texts, graphics and other data.
LAN
(Local Area Network)
Local area network.
Local data traffic is possible in the SINAUT ST7 system via the LAN types "MPI" and
"Industrial Ethernet".
In SINAUT, the LAN is also used as a "WAN", for example when communication via the
Internet is required or when GPRS stations transfer their data onto the Internet to a master
station via a GPRS network.
Local TIM
A TIM connected to a PC (ST7cc, ST7sc) or an S7 CPU over the MPI bus, Industrial
Ethernet or an IP-based network.
LTOP
(Line Transformer with Overvoltage Protection)
Copper dedicated lines are highly susceptible to electromagnetic interference. The coupling
of extraneous voltages can be inductive or capacitive, for example due to the effects of
lightning. Direct conductive coupling is also possible due to bad insulation.
The LTOP overvoltage protection modules limit extraneous voltage and overvoltage to a
non-critical level. The floating transformer also provides electrical isolation preventing
coupling of voltages into other cable sections. An LTOP protects persons and investment
and is therefore an indispensable safety element in private dedicated line networks.
Station control system
System Manual, 07/2009, C79000-G8976-C178-07
maximum of once in the send buffer.
Glossary
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